Communication system

Abstract

To provide a communication system capable of suppressing the influence of a line delay or fluctuation by using an wide area network and realizing communication whose security is secured.SOLUTION: A base communication control device 7 connected to a central radio device 30 and connected to a communication control device 1 via a wide area network is provided, and the base communication control device 7 performs time synchronization for matching base time information of the base communication control device 7 with reference time information of the communication control device 1. The communication control device 1 calculates an arrival time to the base communication control device 7 using the delay information notified from the base communication control device 7, the transmission time, and a reception time of the information, and instructs the base communication control device 7 to advance a transmission start time to the central radio device 30 by the arrival time or more from the transmission start time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wide area network communication system using multiple wireless devices, and more particularly to a communication system that uses a wide area network to reduce the effects of network line delays and fluctuations and achieve secure communication. [Background technology]

[0002] [Prior art: Figure 6] Conventionally, there have been communication systems in which multiple bases are connected via a local network. A conventional communication system will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram showing an example of the configuration of a conventional communication system. As shown in FIG. 6, the conventional communication system performs communication between a point (communication station #1) and another point (communication station #2).

[0003] Communication station #1 and communication station #2 have the same configuration, and each includes a communication control device 10, a VPN (Virtual Private Network) gateway 2, a wireless device 3, an L2 (Layer 2) / L3 (Layer 3) switch 4, and a terminal 5. The communication control device 10 is provided at each base and controls the devices within the base. The VPN gateway 2 performs processes such as encryption / decryption associated with communications in a VPN environment. Wireless device 3 performs wireless communication using high frequency signals with wireless device 2 at another point. Here, wireless communication is performed between wireless device #1 of communication station #1 and wireless device #2 of communication station #2. The L2 / L3 switch 4 transfers data. The terminal 5 is a terminal operated by a user.

[0004] [Radio equipment configuration: Figure 7] The configuration of the wireless device 3 will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram showing the configuration of the wireless device. The radio device 3 includes a modulation / demodulation unit 310 and a high frequency unit 320 . The modem unit 310 performs encryption and modulation / demodulation processing associated with transmission and reception of high frequency signals to and from the communication control device 10 and to and from the outside. The high frequency unit 320 amplifies the modulated signal for transmission and outputs it to the antenna as a transmission high frequency signal, and amplifies, reduces noise, and down-converts the high frequency signal received from the antenna and outputs it to the modulation / demodulation unit 310 .

[0005] The operation of the wireless device 3 will now be briefly described. At the time of transmission, the modulation / demodulation unit 310 of the wireless device 3 receives the encrypted transmission frame and control information (encrypted transmission frame+control) from the communication control device 10, and performs signal processing such as modulation on the encrypted transmission frame in accordance with the modulation method and interleaving method specified in the control information. Then, the modulation / demodulation unit 310 outputs the transmission modulated signal to the high frequency unit 320. High frequency section 310 converts the modulated transmission signal into a high frequency signal, then amplifies the power of the signal and outputs it to an antenna.

[0006] During reception, the high frequency unit 310 reduces noise in the high frequency signal input from the antenna or the like from another communication station, performs demodulation processing and deinterleaving, and outputs the encrypted received frame and reception monitor information (encrypted received frame + monitor) to the communication control device 10. The monitor information is information indicating the operating status of the wireless device 3 obtained from the received signal. The radio equipment 3 transmits monitor information such as operational status to the communication control device 10, and receives control of the frequency setting of the radio equipment from the communication control device 10.

[0007] [Configuration of a conventional communication control device: Figure 8] The functional configuration of a conventional communication control device 10 will be described with reference to Fig. 8. Fig. 8 is an explanatory diagram showing the configuration of a conventional communication control device. As shown in Fig. 8, the conventional communication control device 10 performs various processes associated with communications, and includes functional units (processing means) such as service control means 61 for performing service control, network control means 62 for performing network control, channel control means 63 for performing channel control, data transfer control means 64 for performing data transfer control, wireless access control means 65 for performing wireless access control, VPN gateway IF functional unit 66 for input / output to / from the VPN gateway 2, and communication management means 67 for managing communications. Each functional unit is a functional block realized by software.

[0008] When data is transmitted from the terminal 5 handled by the user to the wireless device 3, the transmission data from the terminal 5 passes through the service control, network control, channel control, data transfer control, wireless access control, and VPN gateway IF functions, and is then transmitted to the wireless device 3 as an encrypted transmission frame (encrypted transmission frame). Furthermore, when an encrypted reception frame (encrypted reception frame) is received from the wireless device 3, the data (terminal reception data) is output to the terminal 5 through a flow reverse to that when transmitting wirelessly.

[0009] In addition, the communication management means 67 performs changes to communication settings, settings to the wireless device 3, and monitoring of the operating status. The communication management means 67 relays control instructions from the terminal 5 to the wireless device 3 and controls each functional unit of the device, and also collects monitor information such as the operating status of the wireless device 3 and the communication status from the functional units of the device, sends it to the terminal 5, and provides the information to the user who operates the terminal 5.

[0010] [Related Technology] As related prior art, there are Japanese Patent Laid-Open No. 2024-046359 "Communication System" (Patent Document 1) and Japanese Patent Laid-Open No. 2024-013480 "Communication System" (Patent Document 2).

[0011] Patent Document 1 discloses a communication system that can perform communication by setting a transmission start time that reflects network fluctuations, even if there are restrictions on the transmission time or transmission period. Furthermore, Patent Document 2 discloses a communication system that adjusts broadcast start times to reflect network fluctuations and changes the distribution method of broadcast data depending on line conditions. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 2024-046359 [Patent Document 2] Japanese Patent Application Publication No. 2024-013480 Summary of the Invention [Problem to be solved by the invention]

[0013] However, conventional communication systems use local networks for communication lines between communication control devices and wireless devices, making it easy to manage line delays and fluctuations and ensure security.However, when trying to use wide area networks, there are problems in that it is difficult to guarantee line delays and fluctuations, and it is also difficult to ensure security between devices.

[0014] Incidentally, Patent Documents 1 and 2 do not describe a configuration for suppressing the effects of line delays and fluctuations using a wide area network and realizing secure communications.

[0015] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a communication system that uses a wide area network to reduce the effects of line delays and fluctuations and realize secure communication. [Means for solving the problem]

[0016] The present invention, which solves the problems of the above-mentioned conventional examples, is a communication system that communicates using a wide area network, and includes a communication control device to which a user's terminal connects, a base communication control device that connects to the communication control device via the wide area network, and a central radio device that connects to the base communication control device, and the base communication control device holds base time information of the base communication control device, requests reference time information of the communication control device from the communication control device, performs time synchronization in accordance with the reference time information returned from the communication control device, obtains radio device delay information which is the delay time in communication with the central radio device, and notifies the communication control device of the radio device delay information, and the communication control device responds with the reference time information in response to the request for reference time information from the base communication control device, and controls communication with the central radio device using the radio device delay information notified from the base communication control device and the arrival time from the base communication control device calculated when the radio device delay information is received, to the base communication control device.

[0017] In addition, the present invention is characterized in that in the above-mentioned communication system, the communication control device uses reference time information and radio device delay information to generate control information for the timing of transmitting data from the base communication control device to the central radio device, and transmits the control information to the base communication control device at a timing that is earlier than the timing by at least the arrival time, thereby controlling the base communication control device.

[0018] Furthermore, the present invention is characterized in that in the above-mentioned communication system, the base communication control device requests the communication control device to establish an encrypted connection, and the communication control device determines an encryption method in response to the request and permits connection with the base communication control device.

[0019] The present invention also provides a base communication control device that is connected to a communication control device via a wide area network and also to a central radio device, the base communication control device comprising a time synchronization unit, a security communication unit, a radio device transmission schedule unit, and a radio reception data time assigning unit, the time synchronization unit retains base time information of the base communication control device from the communication control device, requests reference time information of the communication control device from the communication control device, performs time synchronization according to the reference time information responded from the communication control device, acquires radio device delay information which is the delay time in communication with the central radio device and notifies the communication control device, the security unit performs security processing for communication with the communication control device, the radio device transmission schedule unit transmits the transmission data to the central radio device at a timing specified by control information attached to the transmission data received from the communication control device, calculates the delay time based on the response to the transmission and outputs it as radio device delay information, and the radio reception data time assigning unit assigns time-synchronized base time information to the received data from the central radio device and transmits it to the communication control device. [Effects of the Invention]

[0020] According to the present invention, a communication system for communicating using a wide area network comprises a communication control device to which a user terminal is connected, a base communication control device connected to the communication control device via the wide area network, and a central radio device connected to the base communication control device, wherein the base communication control device holds base time information of the base communication control device, requests reference time information of the communication control device from the communication control device, performs time synchronization in accordance with the reference time information returned from the communication control device, acquires radio device delay information which is the delay time in communication with the central radio device, and notifies the communication control device of the radio device delay information, and the communication control device responds with the reference time information in response to the request for reference time information from the base communication control device, and controls communication with the central radio device by the base communication control device using the radio device delay information notified from the base communication control device and the arrival time from the base communication control device calculated when the radio device delay information is received. This communication system allows the communication control device to acquire various delay information on the side of each base communication control device and perform time management, and even when a wide area network is used, communication control can be performed which reflects fluctuations in network delay as in the case of a local network, thereby ensuring the quality and reliability of service.

[0021] Furthermore, according to the present invention, the communication control device uses reference time information and radio device delay information to generate control information for the timing of transmitting data from the base communication control device to the central radio device, and transmits the control information to the base communication control device at a timing that is earlier than the timing by at least the arrival time, thereby controlling the base communication control device, thereby achieving the effect of managing the delay time in the wide area network as the arrival time and achieving good communication control.

[0022] Furthermore, according to the present invention, the base communication control device requests the communication control device to establish an encrypted connection, and the communication control device determines the encryption method in response to the request and permits connection with the base communication control device, thereby achieving the effect of enabling secure communication even when using a wide area network. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of the present system. [Figure 2] FIG. 2 is an explanatory diagram showing the configuration of the present communication control device. [Figure 3] FIG. 2 is an explanatory diagram showing the configuration of a base communication control device; [Figure 4] FIG. 10 is an explanatory diagram showing a sequence of time synchronization and delay time acquisition. [Figure 5] FIG. 10 is an explanatory diagram showing a transmission and reception sequence. [Figure 6] FIG. 1 is an explanatory diagram illustrating an example of the configuration of a conventional communication system. [Figure 7] FIG. 1 is an explanatory diagram showing the configuration of a wireless device. [Figure 8] FIG. 1 is an explanatory diagram showing the configuration of a conventional communication control device. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention will be described with reference to the drawings. [Outline of the embodiment] A communication system (this system) according to an embodiment of the present invention is a communication system that connects a central base and other bases using a wide area network, and includes a central radio device that connects to the radio devices of the other bases, and a base communication control device that is connected to the central radio device and also connected to the communication control device via the wide area network. The base communication control device holds base time information for the base communication control device, requests reference time information for the communication control device from the communication control device, and performs time synchronization to match the base time information with the reference time information according to the reference time information returned from the communication control device. It also acquires delay information in communication with the central radio device and notifies the communication control device of the delay information with a transmission time. The communication control device responds with reference time information in response to the request for reference time information from the base communication control device, calculates the arrival time at the base communication control device using the delay information notified from the base communication control device, its transmission time, and the reception time of the information, and instructs the base communication control device to start transmission to the central radio device at a time equal to or greater than the arrival time. Even when a wide area network is used, communication control that reflects fluctuations in network delays can be performed, ensuring the quality and reliability of service.

[0025] In addition, in this communication system, the base communication control device requests an encrypted connection from the communication control device, and the communication control device determines the encryption method in response to the request and allows connection with the base communication control device, thereby ensuring security even when using a wide area network.

[0026] [System configuration: Figure 1] The configuration of this system will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing the configuration of this communication system. As shown in Figure 1, this system enables communication between a terminal at a central communication station and terminals at multiple other base stations (base communication station #1, ... base communication station #N) via a wide area network (WAN).

[0027] The central communication station comprises a central base station and wireless equipment installation bases #1 to #N, and the central base station equipment is connected to the wireless equipment installation bases via a wide area network. The central base is provided with a communication control device 1, a VPN gateway 2, an L2 / L3 switch 4, and a terminal 5. The configuration and operation of the communication control device 1 are different from conventional ones, and will be described later.

[0028] The wireless device installation base includes a central wireless device 30 (central wireless device 30-1, ... 30-N) that performs wireless communication with the wireless devices 3 of the base communication stations, and a base communication control device 7 (base communication control device 7-1, ... 7-N) that is connected to each central wireless device 30 by wire. The base communication control device 7 is a characteristic part of this system, and is provided in one-to-one correspondence with each base communication station, and even if there are multiple wireless devices 3 in the same base communication station, there is no need to provide one for each wireless device 3. The configuration and operation of the base communication control device 7 will be described later. The central radio device 30 has the same configuration as the conventional radio device 3.

[0029] The configuration of base communication stations #1, ... #N is the same as the configuration of the conventional communication station shown in Fig. 6, and includes a communication control device 10, a VPN gateway 2, a wireless device 3, an L2 / L3 switch 4, and a terminal 5. The same parts as in Fig. 6 are assigned the same reference numerals, and their explanations will be omitted.

[0030] Before specifically explaining the configuration of this system, the features of the operation of this system will be briefly explained. In this system, time synchronization is performed between the communication control device 1 and the base communication control device 7, and transmission delays and processing delays between the base communication control device 7 and the central radio device 30 are grasped, and the communication control device 1 specifies the start time for transmission to the central radio device 30 to the base communication control device 7 so that communication can be carried out.

[0031] Here, the communication control device 1 acquires the transmission time (arrival time) between the communication control device 1 and the base communication control device 7, and transmits an instruction to the base communication control device 7 at a timing earlier than the transmission start time by that amount. This makes it possible to carry out communications that take into account fluctuations in network delays even when communications are carried out over a wide area network.

[0032] Furthermore, in this system, communication between the communication control device 1 and the base communication control device 7 is performed with security ensured by authentication and encryption processing. Furthermore, in this system, when the communication control device 1 receives a response from the base communication control device 7 to the transmission information specifying the transmission start time, it determines whether retransmission is necessary and the order in which the data should be transmitted based on the reception time at the central radio device 30 attached to the received data, and so on, and decides the data to be transmitted.

[0033] [Configuration of this communication control device: Figure 2] Next, the functional configuration of the communication control device (this communication control device) 1 of this system will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram showing the configuration of this communication control device. This communication control device 1 comprises service control means 11, network control means 12, channel control means 13, VPN gateway IF function unit 16, and communication management means 17 as the same parts as in the conventional device. Furthermore, the communication control device 1 is characterized by a time synchronization control function unit 18, a radio transmission data time assignment / reception data time analysis function unit 19, and a security communication function unit 20, and the data transfer control unit 14 and the radio access control unit 15 operate in a partially different manner from conventional units. These will be described later. Each functional unit is a functional block realized by software.

[0034] The characteristic features of this communication control device 1 will be described. The time synchronization control function unit 18 stores information about the reference time of the communication control device 1 (reference time information) and controls time synchronization with the base communication control device 7. The time synchronization control function unit 18 transmits the reference time information to the base communication control device 7 in response to a request from the base communication control device 7. This time synchronization can be achieved using a network, with a time difference of several milliseconds allowed, and this time difference is the base time difference.

[0035] In addition, the time synchronization control function unit 18 receives the transmission delay and processing delay time (referred to as radio device delay) in communication between the base communication control device 7 and the central radio device 30 and the base time difference from the base communication control device 7, and outputs them to the radio transmission data time assignment / received data time analysis function unit 19.

[0036] Furthermore, when the time synchronization control function unit 18 receives wireless device delay and the like from the base communication control device 7, it calculates the transmission time (referred to as the arrival time) between the communication control device 1 and the base communication control device 7 from the time when the received information was sent from the base communication control device 7 corrected by the base time difference and the reception time, and outputs the calculated time to the wireless device transmission data time assignment / reception data time analysis function unit 19. In other words, the arrival time corresponds to the actual transmission time between the base communication control device 7 and the communication control device 1, regardless of whether there is a base time difference. The arrival time may be calculated by the wireless device's transmission data time assignment / reception data time analysis function unit 19.

[0037] The arrival time includes delays in the wide area network, and in this system, by controlling wireless communication that reflects the arrival time between the communication control device 1 and the base communication control device 7, even if there are delay fluctuations due to the amount of transmission in the wide area network, this can be absorbed and good communication can be achieved.

[0038] The wireless device transmission data time stamping / reception data time analysis function unit 19 stores the wireless device delay, the base time difference, and the arrival time for each base communication control device 7 . Then, the radio transmission data time assignment / reception data time analysis function unit 19 calculates the transmission start time of the radio transmission data (encrypted transmission frame + control information from the VPN gateway IF function unit 16) to be sent from the base communication control device 7 to the central radio device 30, and instructs the base communication control device 7 of the transmission start time.

[0039] At this time, the wireless device transmission data time assignment / reception data time analysis function unit 19 outputs the transmission data (encrypted transmission frame + control information) with the transmission start time assigned to it to the security communication function unit 20, advancing the arrival time from the transmission start time by at least the arrival time. As a result, even if there is a transmission delay in the wide area network, the transmission data from the communication control device 1 is received by the base communication control device 7 before the transmission start time, and is output from the base communication control device 7 to the central radio device 30 at a transmission start time that takes into account the processing delay of the central radio device 30, so that wireless transmission can be started from the central radio device 30 at the time set by the wireless access control means 15.

[0040] In addition, when the radio transmission data time assignment / reception data time analysis function unit 19 receives reception data from the radio device 3 of the base communication station from the base communication control device 7, it calculates the time when the central radio device 30 received the data wirelessly based on the time information in the monitor information included in the received data, and outputs the reception time (radio reception time) to the radio access control means 15 and the data transfer control means 14. The data transfer control means 14 determines whether reception at the central radio device 30 has been successful or not, based on the radio reception time, and whether the reception time has expired, and determines the data to be transmitted.

[0041] The security communication function unit 20 controls security communications with the base communication control devices 7, and authenticates all information including data, control information, and device operating status to each base communication control device 7, performs predetermined encryption processing, and outputs the information to an edge server connected to the wide area network. The encryption processing method is an existing method. The security communication function unit 20 manages authentication information and encryption keys, and when a request for an encrypted connection is received from the base communication control device 7, the security communication function unit 20 judges the authentication information of the base communication control device 7, determines the encryption method, and permits the connection.

[0042] In addition, when security-processed data is received from the base communication control device 7, authentication is confirmed, decryption processing is performed, and the data is output to the radio transmission data time stamping / reception data time analysis function unit 19, and when the device operation status is received, decryption processing is performed and the data is output to the communication management means 17.

[0043] In addition to the conventional operations, the radio access control unit 15 sets the transmission time of the encrypted transmission frame+control information in the radio transmission data time setting / reception data time analysis function unit 19 .

[0044] [Operation of the communication control device: Figure 2] The operation of this communication control device 1 will be explained, focusing on the differences from the conventional technology. First, when the time synchronization control function unit 18 receives a request for the reference time from the base communication control device 7 (time information acquisition request), it responds with the reference time (time information acquisition response). Then, the time synchronization control function unit 18 outputs the reference time information stored internally, the radio device delay obtained from the base communication control device 7, the base time difference, and the arrival time at the base communication control device 7 obtained through communication with the base communication control device 7 to the radio transmission data time assignment / received data time analysis function unit 19.

[0045] When transmitting to a base communication station, the radio transmission data time assignment / reception data time analysis function unit 19 calculates the transmission start time for the base communication control device 7 for the encrypted transmission frame input from the VPN gateway IF function unit 16 so that transmission begins at the transmission time set by the wireless access control means 15 in the central wireless device 30.

[0046] Specifically, the radio transmission data time assignment / reception data time analysis function unit 19 first subtracts (advances) the stored radio device delay time from the set transmission time, corrects the result by the base time difference, and sets the corrected time as the transmission start time at which the base communication control device 7 starts transmission to the central radio device 30. Then, at a timing (advanced timing) earlier than the transmission start time by at least the arrival time, data with the set transmission start time is output to the security communication function unit 20. The transmission timing of this encrypted transmission frame + control information is not affected by the presence or absence of a base time difference.

[0047] Then, security processing is performed in the security communication function unit 20, and the security-processed transmission data is transmitted to the base communication control device 7 via the edge server and the wide area network. By setting the timing of transmission from the communication control device 1 to the base communication control device 7 to the time obtained by subtracting (advancing) the stored arrival time from the transmission start timing at the base communication control device 7, it is possible to perform transmission taking into account the delay time in the wide area network between the communication control device 1 and the base communication control device 7. Furthermore, by frequently calculating the arrival time, it is possible to compensate for fluctuations in delay in wide area networks.

[0048] When receiving from the base communication station, the security-processed received data is decrypted by the security communication function unit 20, and the encrypted received frame and monitor information are input to the radio transmission data time stamping / received data time analysis function unit 19. The radio transmission data time stamping / received data time analysis function unit 19 calculates the reception time at the central radio device 30 from the time information included in the monitored information, and outputs it to the data transfer control means 14 and the radio access control unit 15 as the radio reception time.

[0049] On the other hand, the encrypted received frame is decrypted by the VPN gateway IF function unit 16, the received frame is extracted, and is output to the terminal 5 as received data via data transfer control, channel control, network control, and service control.

[0050] [Configuration of the base communication control device: Figure 3] Next, the configuration of the base communication control device 7 will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing the configuration of the base communication control device. As shown in FIG. 3, the base communication control device 7 includes a security communication function unit 31, a time synchronization function unit 32, a wireless device received data time stamp function unit 33, and a wireless device transmission schedule function unit .

[0051] The security communication function unit 31 requests an encrypted connection from the communication control device 1, and if permitted, performs security processing to authenticate and encrypt the data and device operating status information to be sent to the communication control device 1, similar to the security communication function unit 20 of the communication control device 1. In addition, the security-processed information from the communication control device 1 is decrypted, and the encrypted transmission frame + control information (transmission start time, etc.) shown by the solid line is output to the wireless device transmission schedule function unit 34, and the control information shown by the dotted line is output to the central wireless device 30.

[0052] The time synchronization function unit 32 performs time synchronization when communication with the communication control device 1 starts, holds base time information internally, and provides the time information to each unit in the device. When communication starts, a time information acquisition request is output to the communication control device 1, and when reference time information is acquired from the communication control device 1, a time synchronization process is performed to synchronize the internal base time information with the reference time information. As described above, this system allows a time difference of several milliseconds, and this time difference is used as the base time difference. Furthermore, the synchronized time function unit 32 transmits to the communication control device 1 the base time difference and the value of the radio device delay, which will be described later.

[0053] The radio device transmission schedule function unit 34 outputs the encrypted transmission frame to the central radio device 30 in accordance with the transmission start time designated by the communication control device 1 . It also receives a response from the central radio device 30, calculates the communication delay and internal processing delay based on the time from transmission to reception of the response, and outputs the calculated delay to the time synchronization function unit 32 as the radio device delay.

[0054] When the central radio device 30 receives data (encrypted reception frame + monitor information) from the base communication station, the radio device reception data reception time assignment function unit 33 assigns time information from the time synchronization function unit 32 to the information as the transmission time and transmits it to the communication control device 1 via the security communication function unit 31.

[0055] [Operation of the base communication control device: Figure 3] Next, the operation of the station communication control device 7 will be described with reference to FIG. At the start of communication, the time synchronization function unit 32 transmits a time information acquisition request to the communication control device 1, and upon receiving a time information acquisition response from the communication control device 1, synchronizes the base time information with the reference time. At that time, the difference from the reference time is stored as the base time difference.

[0056] In addition, the wireless device transmission schedule function unit 34 transmits control information for acquiring the wireless device delay to the central wireless device 30, and when it receives a response from the central wireless device 30, it calculates the wireless device delay, and the time synchronization function unit 32 transmits information on the wireless device delay and the base time difference to the communication control device 1.

[0057] When transmitting to a base communication station, the security-processed transmission data from the communication control device 1 is decrypted by the security communication function unit 31 and input to the radio device transmission schedule function unit 34 as an encrypted transmission frame + control information.The radio device transmission schedule function unit 34 then suspends sending to the central radio device 30 until the specified transmission start time arrives, and transmits to the central radio device 30 at the specified transmission start time.

[0058] When receiving from a base communication station, the encrypted received frame + monitor information from the central radio device 30 is given a transmission time in the radio device received data time assignment function unit 33 and transmitted to the communication control device 1 via the security communication function unit 31.

[0059] [Time synchronization and delay time acquisition sequence: Figure 4] Next, the sequence of time synchronization and delay time (wireless device delay and arrival time) acquisition in this system will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing the sequence of time synchronization and delay time acquisition. As shown in FIG. 4, when the communication control device 1 transmits a time synchronization update notification to the station communication control device 7 (S11), the station communication control device 7 transmits a time information acquisition request to the communication control device 1 (S12).

[0060] When the communication control device 1 receives the time information acquisition request, it sends a time information acquisition response including the reference time information of the communication control device 1 to the base communication control device 7 (S13), and the base communication control device 7 synchronizes its internal base time with the received reference time (S14). The transmission and reception between the communication control device 1 and the base communication control device 7 up to this point is performed without going through the security communication function units 20 and 31.

[0061] Then, the base communication control device 7 transmits control information (response request) to the central radio device 30 to acquire the communication delay and processing delay (S15), and the central radio device 30 receives this and transmits a response to the base communication control device 7 (S16). The base communication control device 7 calculates the processing delay based on the sending time of S15 and the response receiving time of S16, and sends the processing delay as the wireless device delay to the communication control device 1 with the time information from the time synchronization function unit 32 attached as the sending time (S17). Although not shown in the figure, the base time difference is also sent in processing S17.

[0062] Furthermore, the central radio device 30 may be configured to send a response when it receives a response from the base communication control device 7, and after generating the token ring, when the base communication control device 7 sends the encrypted transmission frame + control information to the central radio device 30, the base communication control device 7 may calculate the radio device delay based on the time it received the response, and send it to the communication control device 1 with the transmission time attached.

[0063] The communication control device 1 receives the information on the radio device delay, and stores the received value (information) of the radio device delay and the base time difference corresponding to the base communication control device 7 and the central radio device 30. Furthermore, the communication control device 1 calculates the arrival time between the communication control device 1 and the base communication control device 7 from the transmission time (transmission time from the base communication control device 7) attached to the information on the wireless device delay corrected by the base time difference and the reception time at the communication control device 1, and stores the calculated time in correspondence with the base communication control device 7 and the central wireless device 30 (S18). In this way, the sequence of time synchronization and delay time acquisition is performed.

[0064] [Transmission and reception sequence: Figure 5] Next, the transmission and reception sequence of this system will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing the transmission and reception sequence. Note that in Fig. 5, the base communication station is the same as in the conventional system, so it is not shown. FIG. 5 shows the state after a token ring has been generated between the terminal at the central station and the terminal at the local communication station. When data is transmitted from the terminal 5 at the central site, the communication control device 1 transmits the data and token together with the transmission start time to the local communication control device 7 (S21). At this time, the communication control device 1 transmits the data to the station communication control device 7 earlier than the transmission start time by at least the amount of time it takes for the data to reach the station communication control device 7 from the communication control device 1.

[0065] When the local communication control device 7 receives the data+token, it waits for transmission until the transmission start time arrives (waits for transmission time schedule) (S22), and when the transmission start time arrives, it transmits the token+data to the central radio device 30 (S23). The central radio device 30 transmits the token and data to the radio device 3 (not shown) of the base communication station.

[0066] Then, when the central radio device 30 receives the token from the radio device 3 of the base communication station, it transmits the token to the base communication control device 7 (S24), and the base communication control device 7 assigns a transmission time (S25) and transmits a token reception notification to the communication control device 1 (S26). The communication control device 1 determines whether reception at the base communication station was successful or not and whether the response time has expired based on the transmission start time, the transmission time from the base communication control device 7, and the radio reception time in the monitor information included in the received data, and determines whether retransmission is necessary and decides the data to be transmitted.

[0067] [Effects of the embodiment] According to this system, a communication system that connects a central base and other bases using a wide area network is provided, and the system includes a central radio device 30 that connects to radio devices 3 at other bases, and a base communication control device 7 that is connected to the central radio device 30 and also connected to a communication control device 1 via the wide area network. The base communication control device 7 holds the base time information of the base communication control device 1, requests the communication control device 1 for reference time information of the communication control device, and performs time synchronization to match the base time information with the reference time information according to the reference time information returned from the communication control device 1, and also acquires delay information in communication with the central radio device 30 and calculates the delay. The communication control device 1 notifies the communication control device 1 of the delay information with the transmission time attached to it, and the communication control device 1 responds with the reference time information in response to a request for reference time information from the base communication control device 7, calculates the arrival time at the base communication control device 7 using the delay information notified from the base communication control device 7, its transmission time, and the reception time of the information, and instructs the base communication control device 7 to start transmission to the central radio device 30 at least as early as the arrival time from the transmission start time.This has the effect of enabling communication control that reflects fluctuations in network delay even when a wide area network is used, and ensuring the quality and reliability of service.

[0068] Furthermore, according to this system, the base communication control device 7 requests an encrypted connection from the communication control device, and the communication control device 1 determines the encryption method in response to the request and permits connection with the base communication control device 7, which has the effect of ensuring security even when using a wide area network. [Industrial Applicability]

[0069] The present invention is suitable for a communication system that uses a wide area network to suppress the effects of line delays and fluctuations and achieves secure communication. [Explanation of symbols]

[0070] DESCRIPTION OF SYMBOLS 1,10...Communication control device, 2...VPN gateway, 3...Radio device, 4...L2 / L3 switch, 5...Terminal, 11,61...Service control means, 12,62...Network control means, 13,63...Channel control means, 14,64...Data transfer control means, 15,65...Radio access control unit 15, 16,66...VPN gateway IF function unit, 17,67...Communication management means, 18...Time synchronization control function unit, 19...Radio device transmission data time assignment / reception data time analysis function unit, 20,31...Security communication function unit, 30...Central radio device, 32...Time synchronization function unit, 33...Radio device reception data time assignment function unit, 34...Radio device transmission schedule function unit

Claims

1. A communication system that communicates using a wide area network, a communication control device to which a user terminal is connected; a base communication control device connected to the communication control device via the wide area network; a central wireless device connected to the site communication control device, The base communication control device holds base time information of the base communication control device, requests reference time information of the communication control device from the communication control device, performs time synchronization according to the reference time information returned from the communication control device, acquires radio equipment delay information which is a delay time in communication with the central radio equipment, and notifies the communication control device of the radio equipment delay information; A communication system characterized in that the communication control device responds with reference time information in response to a request for the reference time information from the base communication control device, and controls communication between the base communication control device and the central radio device using the radio device delay information notified from the base communication control device and the arrival time from the base communication control device calculated when receiving the radio device delay information.

2. The communication system described in claim 1, characterized in that the communication control device uses the reference time information and the radio device delay information to generate control information for the timing of transmitting data from the base communication control device to the central radio device, and transmits the control information to the base communication control device at a timing that is earlier than the timing by at least the arrival time, thereby controlling the base communication control device.

3. the base communication control device requests the communication control device to establish an encrypted connection; 3. The communication system according to claim 1, wherein the communication control device determines an encryption method in response to the request and permits connection with the base communication control device.

4. A base communication control device that is connected to a communication control device via a wide area network and also connected to a central wireless device, the base communication control device includes a time synchronization unit, a security communication unit, a wireless device transmission schedule unit, and a wireless reception data time setting unit; the time synchronization unit holds base time information of the base communication control device from the communication control device, requests reference time information of the communication control device from the communication control device, performs time synchronization according to the reference time information returned from the communication control device, and also acquires radio device delay information which is a delay time in communication with the central radio device and notifies the communication control device of the same; the security unit performs security processing for communication with the communication control device, the wireless device transmission scheduler transmits the transmission data received from the communication control device to the central wireless device at a timing designated by control information attached to the transmission data, calculates the delay time based on a response to the transmission, and outputs the calculated delay time as the wireless device delay information; the wireless reception data time assigning unit assigns the time-synchronized base time information to the reception data from the central wireless device and transmits the data to the communication control device. A base communication control device characterized by:

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